You can only listen to mixes in Pacemaker made with Spotify tracks with a Spotify Premium subscription. Once your free trial expires, purchase Spotify Premium from their website: www.spotify.comSpotify will only allow you to use one device at a time, so you can install Pacemaker on multiple phones or iPads, but you will only be able to play back Spotify tracks on one device at a time. Other devices will be paused. Hope that helps!